Performance enhancement of perovskite solar cells by doping TiO2 blocking layer with group VB elements

Hole blocking layer with pinhole-free and excellent electron conductivity is critical in high-efficient perovskite solar cells. In this paper, we investigated thoroughly the effect of tantalum (Ta) or niobium (Nb) dopant in TiO2 compact layer. Both Ta and Nb dopants could enhance the electron conductivity of TiO2 compact film without declining their light transmittance property. The PSCs assembled with Ta or Nb-doped TiO2 blocking layer exhibited an evident promotion in short-circuit current density, and the best-performing PSCs had conversion efficiency enhancement from 13.66% (pure TiO2) to 14.41% (Ta-doped TiO2) and 14.29% (Nb-doped TiO2). Moreover, the reproducibility of PSCs was preferable with 3% Ta and 3% Nb-doped TiO2 blocking layer. Besides, the increased conductivity of doped TiO2 compact layer efficiently suppressed the J-V hysteresis of PSCs under different scan directions. PL and EIS results further revealed that the doped TiO2 compact layer could accelerate electron transfer rate and decrease the recombination probability at TiO2/perovskite interface. (C) 2016 Elsevier B.V. All rights reserved.